FR2575253A1 - HYDRAULIC ANTIVIBRATORY SUPPORT - Google Patents

Abstract

THIS IS A HYDRAULIC ANTI-VIBRATION SUPPORT INTERPOSED BETWEEN A CHASSIS AND A VEHICLE ENGINE, INCLUDING A WORK CHAMBER A AND A COMPENSATION CHAMBER B FILLED WITH LIQUID AND JOINED BETWEEN A STRANGLE PASSAGE 6, THE DIMENSIONS OF THIS PASSAGE, AND THEREFORE THOSE OF THE CORRESPONDING LIQUID COLUMN, DETERMINING THE FREQUENCY OF OSCILLATIONS THE BEST AMORTED BY THE MOVEMENTS OF THIS COLUMN. TO INCREASE THE NUMBER OF OSCILLATORY PHENOMENA LIKELY TO BE CUSHIONED EXCELLENTLY BY "COLUMN" EFFECT, AT LEAST ONE SECOND STRANGLE PASSAGE 8, 8 MOUNTED IN PARALLEL OVER AT LEAST PART OF THE LENGTH OF THE FIRST 6.

Description

Hydraulic anti-vibration support.

  The invention relates to anti-vibration devices.

  roofs intended to be interposed for support purposes and

  damping between two rigid elements, the damping

  ment involving the discharge of a liquid through

  towards a constricted passage, and the relative displacements to dampen two rigid elements comprising on the one hand relatively large amplitude oscillations (that is to say

  greater than mm) at relatively low frequency (i.e.

  say less than 20 Hz) and on the other hand vibrations of relatively small amplitude (i.e. less than

  0.5 mm) at relatively high frequency (i.e. higher than

less than 20 Hz).

  By way of nonlimiting example, it is indicated that such supports can be mounted between a chassis of

  vehicle and the engine of that vehicle, the oscillations

  tively ample to amortize being those created by the irre-

  irregularities and variations in gradient of the ground during the

  culation of the vehicle on this ground and the vibrations to be damped

  being those due to the operation of the engine.

  The invention relates more particularly, by-

  mi supports of the genre in question, those that are

  killed by a waterproof case interposed between the two elements

  rigid elements, housing comprising two rigid rigid parts

  darisables respectively with the two rigid elements, a first elastic wall sealingly connecting one

  of the two rigid parts to a rigid annular reinforcement made

  being part of the second part, this first wall delimits

  mitting with the first part one of the two axial ends of the shoemaker and ensuring the role of support between the two parts, for which it has good resistance to axial compression, a second elastic wall carried in a sealed manner by the frame annular and delimiting

  the second axial end of the shoemaker, a deformed partition

  ble also carried in a sealed manner by the an-

  ring, between the two elastic walls, and dividing the

  inside the housing in two chambers, namely a

  work between the partition and the first elastic wall

  tick and a clearing house between the

  sound and the second elastic wall, these two communal chambers

  connecting between them by the constricted passage above, means for limiting to a small amplitude, that is to say less than 1 mm, the deformations of the partition in the axial direction perpendicular to its mean plane, and a mass liquid filling both chambers and the

strangled passage.

  With such a support, a frequency vibration

  high and low amplitude exerted between the two elements

  rigid elements generates corresponding relative displacements

  dants of the two rigid parts, which are transmitted to the deformable partition by the liquid contained in the

  work and result in a rapid succession of deformation

  alternative mations of this partition perpendicularly

  to itself, of amplitude lower than the maximum value pos-

  sible: the dimensions of the partition are chosen sufficient

  so that it can absorb the displacements

  signaled without the liquid being pumped through the passage throttled in opposite directions in synchronism

with vibration.

  On the contrary, for oscillations of higher amplitude and lower frequency, the amplitude of

  corresponding deformations of the partition reaches its

  their maximum possible and the liquid is then forced back through the constricted passage, which ensures damping

  hydraulic of this liquid by its constriction in this passage.

  In the known embodiments of the supports in question, the constricted passage is a channel which delimits a liquid mass comparable to a column of diameter and

relatively large in length.

  In general, this channel is hollowed out in the annular reinforcement of the support and extends in an arc of circle of between 45 and 350 around the deformable partition, the two ends of the channel being terminated by fittings which

  lead into the two bedrooms respectively.

  The channel in question is unique so that the report

  port R between its length and its diameter, general ratio-

  between 2? and 100, is determined once and for all. However, experience shows that the resonance frequency F of the column of liquid contained in such a channel is linked to said ratio R as well as the amplitude A of the oscillations.

to amortize.

  We cannot therefore amortize correctly, with the sup-

  known ports of the genus considered, that an oscillatory phenomenon

  re well determined, corresponding to a frequency and a

amplitude well determined.

  This is how, for example, if the frequency F1 chosen to define the ratio R is that, known as hash, of the order of 10 Hz, which corresponds to the most unpleasant vibrations transmitted to the seats of the users during the rolling of the vehicle concerned, only the oscillations corresponding to this frequency F1 and to well-defined amplitudes A1, for example greater than a threshold of the order of 0.3 mm, will be damped under the conditions

optimal.

  In other words, the supports considered do not

  do not dampen the corresponding oscillations at best

  at the frequency F1 but at amplitudes other than A1, for example of the order of 0.1 mm and / or at the same amplitudes A1, but at other frequencies than F1, for example at a frequency of the order 25 Hz, as is the case for

  vibrations emitted at idle by certain Diesel engines.

  The object of the invention is to broaden the capacity to absorb

  weaving of the supports considered by extending it to a number

  higher frequencies and / or amplitudes of oscillations.

  To this end, the supports of the genre in question are essentially characterized according to the invention in that they present, to establish communication between the two

  chambers, at least one second constricted passage mounted in the

  rallies over at least part of the length of the first

strangled passage.

  In preferred embodiments, recourse is also had to one and / or the other of the following arrangements: the second constricted passage is a channel delimiting a second column whose section is less than that of the first column , - the second constricted passage is a channel delimiting a second column whose length is less than that of the first column, - the second constricted passage is defined by a small hole connecting one of the two chambers to a point of the first passage, - the above point of the first passage is at the end of the latter, connected to the other chamber,

  - the second passage includes two holes of the above type

  above respectively connecting the two chambers at two points, distinct or combined, of the first passage, - the second passage is defined by a small hole drilled in the deformable partition, - each of the holes constituting a second passage

  is oriented parallel to the axis of the annular armature.

  The invention includes, apart from these main provisions, certain other provisions which are used

  preferably at the same time and which will be more explicit-

question below.

  In the following, modes of reaction will be described.

  References of the invention with reference to the drawing

  appended hereto of course in a nonlimiting manner.

  Figure 1, of this drawing, shows in schematic axial section an anti-vibration hydraulic support established

according to the invention.

  Figures 2 and 3 are developed sections of

  the first column included by such a support, cuts weakly

  appearing the locations of the second columns

  blies according to respectively two different variants of the invention. The support considered is intended to be interposed vertically between a rigid carrier member which will be assumed hereinafter to be a vehicle chassis and a rigid supported member which will be assumed thereafter to be

an internal combustion engine.

  This support is in the general form of a waterproof case comprising, in a manner known per se: - an annular frame 1 connected. below a perforated tray 11 itself secured to a central bolt 12 allowing assembly on the chassis of the vehicle,

  - a rigid cap 2 appearing here in the form

  me of a bolt whose threaded portion extends upwards, bolt which can be secured to the motor housing, - a thick frustoconical wall 3 in

  rubber or similar elastic material adhered respec-

  tively on the frame 1 and on the cap 2 and capable of resisting elastically to axial compression and. to transverse bending, - and a tight elastic wall 4 whose periphery

  is tightly fixed to the annular frame 1.

  A deformable partition 5 divides the interior of the housing into two chambers A and B both filled with a damping liquid, namely a working chamber A,

  disposed on the side of the wall 3 and a chamber B, of compensating

  sation, arranged on the side of the wall 4.

  The partition 5 is constituted by a membrane 51 mounted on an annular seat 52 which is secured to

annular reinforcement 1.

  The deflections of this membrane are limited in any desirable manner, for example by incorporation

with a metallic canvas.

  The communication of the liquid between the two chambers A and B takes place through a constricted passage 6 constantly open.

  This passage is formed by a hollowed-out channel inside

  inside of the seat 52 and extending in an arc of a circle between 60 and 350, channel including the. two ends lead respectively into the two chambers A and B by

two fittings 61 and 62.

  Finally we advantageously provide in the room

  Has a perforated plate 7 extending parallel to the mem-

  brane 51, at a small distance from it and bearing

  at its periphery on seat 52.

  As indicated above, the support which has just been described makes it possible to absorb:

  - on the one hand, relative frequency oscillations-

  ment low F1 and relatively large amplitude A1,

  - on the other hand, vibrations at relative frequency-

  ment high F2 and relatively small amplitude A2.

  The frequency F1 and the amplitude A1 are determined by the impedance of the column of liquid C1 contained in the passage 6, impedance linked to the ratio R1 between the length and -

the diameter of this column.

  To allow excellent amortization, by ef-

  fet "column", of oscillations having a frequency (F1, F1 ..)

  and / or an amplitude (Ai, A "..) distinct from those indicated

  quées above, according to the invention, there is provided at least a second column (Cl, C ..) in parallel on a part in the hands of the first, the length / diameter ratio of this second column being determined according to the new

  parameters (frequency and / or amplitude) considered.

  In the embodiment illustrated in FIG. 1, this second column is unique and is defined by a small hole B directly connecting the chamber A to the zone 62, of the first column, which opens into the chamber B.

  The diameter of this hole is generally included between-

  be 2 and 6 mm and its length is of the order of 5 mm, being generally less than 10 mm.

  Experience has shown that with a main column

  the 6 having a section of the order of 35 mm and a

  length of the order of 60 mm, the presence of a circular hole

  strip 8 at the location indicated above, a hole with a diameter of 4 mm and a length of 4 mm, had the effect of:

  - on the one hand, to considerably reduce the rigidi-

  support t for frequencies above 30 Hz and in particular for those of the order of 50 Hz, for which the observed reduction is of the order of 50%, - and on the other hand to equalize to the same value frequency, of the order of 40 Hz, the maximum damping efficiencies of the support corresponding respectively to

  "large" amplitudes - namely greater than 0.3 mm -

  and at "small" amplitudes - less than 0.3 mm -, while in the absence of said hole the maxima corresponding to these different amplitudes were dispersed over a range of

  frequencies between 32 and 38 Hz.

  Instead of providing a single small hole 8 in the vicinity-

  ge of one end of the main column 6, one can provide a plurality, which allows to diversify the

  support damping performance.

  In the embodiment shown schematically in Figure 2, these small holes are three in number, designated respectively by the references 81, 82 and 83 and having respectively identical small sections, but different lengths, being drilled respectively between

  on the one hand, a flat face P of the frame 52 'perpendicular to

  laire to the axis of this frame and located on the c6té of the chamber A and on the other hand a stepped and / or oblique face E opposite to said planar face P and partly defining the connector 62 which opens into the chamber B. Au instead of opening the hole constituting the second column in one of the ends of the first column, which amounts to mounting the second column in parallel over the entire first column, it is also possible to open the said hole at an intermediate point of the first column, which goes up this hole in parallel

  on only part of said first column.

  According to another variant, the second column is made to include two holes of the kind defined in the preceding paragraph, connecting the two chambers A and B to respectively

  two points confused or distinct from the first column.

  It is this last hypothesis which has been illustrated.

  in FIG. 3, for which the two holes 8 'and 8 "represent

  link respectively two points M and N of the first column to chamber A and chamber B respectively. The second column can then be considered as the totality of the liquid volume successively contained in hole 8 ', in the section M4N of the first column and

in the 8 "hole.

  According to yet another variant, the second column can be constituted quite simply by a hole drilled in the deformable partition and in particular by a hollow 8x hole

  axially at the center of the membrane 51 in the reaction mode

reading illustrated in figure 1.

  In each case, the choices of location and

  dimensions of the holes delimiting the second column are determined

  born from the knowledge of the relationship between the length and the diameter (or the section) of this second column, relationship which is related to the frequency and the amplitude of the oscillatory phenomenon which one wishes to dampen at best by putting

  in resonance of said second column.

  Following this, and whatever the mode of reaction

  lization adopted, we finally have a hydraulic support

  anti-vibration policy, the constitution of which at least two columns and the operation result sufficiently from this

who is before.

  This support has a number of advantages over those previously known, and in particular the following: - it provides excellent damping by "column" effect of several oscillatory phenomena having distinct frequencies and / or amplitudes: this is how a support with two columns in accordance with the invention makes it possible to absorb in an excellent manner by "column" effect both certain hash oscillations (having a frequency of 10 Hz and an amplitude greater than 0.5 mm) as well as certain vibrations of engine operating at idle (with a frequency of 25 Hz and an amplitude less than 0.5 mm); - The frequencies and / or amplitudes of at least some of the oscillatory phenomena in question, damped by the "column" effect, can be found in the field which, in previously known supports, was considered to be dampable by the vibrations of the deformable partition; - the cost price of the support considered is not higher than that of comparable supports comprising a

  single column since the small holes making up the se-

  these columns are hollowed out in parts obtained by molding. As goes without saying, and as it already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have

  been more specifically contemplated; she embraces it,

milk, all variants.

Claims (8)

  1. Anti-vibration device intended to be in-   terposed for the purposes of support and damping between two rigid elements, consisting of a sealed housing filled with liquid interposed between the two rigid elements, housing comprising two rigid parts (1, 2) which can be joined together   respectively with the two rigid elements, a first   re elastic wall (3) sealingly connecting one of the   two rigid pieces (2) with an annular frame (1) made   being part of the other room and ensuring the role of support   between the two parts, a second elastic wall (4) carrying   tightly sealed by the annular reinforcement, a partition   its deformable (5) also carried in a sealed manner by the annular reinforcement, between the two elastic walls, and dividing the interior of the shoemaker into two chambers (A, B), namely a working chamber (A) included between the partition deformable and the first elastic wall and a compensation chamber (B) between the deformable partition and the second elastic wall, these two chambers communicating with each other by a constricted passage (6) and means for limiting to a low amplitude, c '' i.e. less than 1 mm, the deformations of the deformable partition according to the   axial direction perpendicular to its mean plane, charac-   terized in that it has, to establish the passage between the two chambers (A and B), at least one second constricted passage (8) mounted in parallel on at least part of   the length of the first strangled passage (6).   2. Device according to claim 1, in the-   which the first strangled passage is a channel which delimits   te a mass of liquid comparable to a column, character-   terized in that the second constricted passage (8) is a ca-   nal delimiting a second column whose section is indistinguishable   lower than that of the first column (6).   3. Device according to claim 1, in the-   which the first strangled passage is a channel which delimits   te a mass of liquid comparable to a column, character-   terized in that the second constricted passage (8) is a ca-   nal delimiting a second column whose length is   lower than that of the first column (6).   4. Device according to any one of the preceding-   your claims, characterized in that the second pass   strangled age (8) is defined by a small hole connecting one   of the two rooms (A and B) at a point on the first pass.   5. Device according to claim 4, character-   se in that the point of the first pass is at the ex-   end, of this one, connected to the other room.   6. Device according to any one of the claims.   cations 4 and 5, characterized in that the second passage   includes two holes as defined above connecting res-   pectively the two chambers (A and B) at two points (M and   NOT); distinct or confused, from the first pass.   7. Device according to any one of the preceding-   your claims, characterized in that the second pass   is defined by a small hole (8x) drilled in the deformable partition (5)   8. Device according to any one of the claims.   cations 4 to 7, characterized in that each of the holes   the second passage is oriented parallel to the axis of the annular reinforcement (1).